1. Field of the Invention
The present invention relates to disposable diapers including absorbers, top sheets, back sheets, and skin-contact sheets. The skin-contact sheets are arranged over the top sheets and are provided with openings to allow passage of feces.
2. Description of the Related Art
Recently, disposable diapers including an absorber, a top sheet, and a back sheet have been widely used as diapers for infants and elderly or disabled persons. The top sheet is arranged so as to cover the top surface of the absorber and is at least partially composed of a liquid-permeable material. The back sheet is arranged so as to cover the bottom surface of the absorber and is composed of a liquid-impermeable material. This disposable diaper is worn by a wearer so that the surface of the top sheet is in contact with the skin of the wearer, and thereby urine excreted by the wearer penetrates the top sheet and is absorbed and held by the absorber. The back sheet is superior in the prevention of leakage of excrement, and thereby the leakage of excrement to the outside of the diaper is prevented (see, for example, FIG. 3 in Japanese Patent No. 2572744: Patent Document 1).
However, in a diaper having the above-described structure, urine can penetrate the top sheet, but most feces cannot penetrate the top sheet. Therefore, the feces remain on the top sheet. The remaining feces on the top sheet adhere to the crotch area and buttock area of a wearer, and, consequently, troublesome wiping-off work is required to clean the wearer. This causes an increase in the burden on nursing infants or care-givers, and also causes skin irritation to a wearer. These troubles are further significant when a wearer excretes soft feces.
Accordingly, disposable diapers including an additional sheet (in this specification, termed a “skin-contact sheet”) disposed over the top sheet have been disclosed (see, for example, paragraph 0010 and FIG. 2 in Japanese Utility Model Registration No. 2559050: Patent Document 2, and paragraph 0020 and FIG. 1 in Japanese Unexamined Patent Application Publication No. 2002-11044: Patent Document 3). In these disposable diapers, the skin-contact sheet is provided with an opening (feces-passing opening) allowing passage of feces, and feces excreted by a wearer pass through the feces-passing opening and reach the top sheet.
In the disposable diapers disclosed in Patent Documents 2 and 3, the skin-contact sheet is brought into contact with the skin of a wearer and the top sheet arranged under the skin-contact sheet is negligibly brought into direct contact with the skin of the wearer. Thus, the top sheet is isolated from the skin of a wearer by the skin-contact sheet interposed between the top sheet and the skin of the wearer. That is, the skin-contact sheet serves as a shielding layer. Therefore, it is expected that, even if feces remain on the top sheet, the opportunity that the feces are brought into direct contact with the skin of a wearer is significantly decreased.
However, even if a disposable diaper has a skin-contact sheet described above, urine or soft feces that have reached the top sheet through the skin-contact sheet sometimes exude from the skin-contact sheet and adhere to the skin of a wearer. These occurrences, so-called “urine backflow and feces backflow”, are problematic. In other words, the disposable diaper provided with the skin-contact sheet is not sufficiently satisfactory from the viewpoint of the prevention of urine backflow and feces backflow and therefore still has problems to be solved.
Thus, at present, disposable diapers which can allow the skin of a wearer to be negligibly brought into direct contact with excreted feces and can efficiently prevent urine backflow and feces backflow have not been disclosed yet, and such disposable diapers are desired to be developed. The present invention has been accomplished for solving the problems of the known technologies and provides disposable diapers which can allow the skin of a wearer to be negligibly brought into direct contact with excreted feces and can efficiently prevent urine backflow and feces backflow.